Schedule II Valuation and Qualifying Accounts (Details) (Allowance for Doubtful Accounts [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Allowance for Doubtful Accounts [Member]
Allowance for doubtful accounts:
Balance, beginning of period	$ 12,407		$ 15,284		$ 16,649
Charged to Costs and Expenses	7,064		3,977		5,044
Other	1,754	[1]	2,112	[1]	2,300	[1]
Deductions	10,407	[2]	8,966	[2]	8,709	[2]
Balance, end of period	$ 10,818		$ 12,407		$ 15,284

[1] Allowance for doubtful accounts for companies acquired and recoveries.

[2] Uncollectible accounts written off.